For an application in a computer mouse, mounting a first light source circuit and a second photoreceptor circuit in the same optoelectronic module is already known. The first light source circuit generates light passing through a first aperture in the encapsulation material of the module, whereas the second photoreceptor circuit receives reflected light on an external surface through a second aperture in the encapsulation material. This photoreceptor circuit acting as a sensor generally includes several photosensitive zones for picking up light. The signals from this sensor are usually transmitted to another circuit for processing the sensor signals. Depending upon the quantity and the variation in the light picked up by certain photosensitive zones of the photoreceptor circuit, the processing circuit is able to provide control signals to the computer for moving a cursor on the computer screen.
EP Patent Application Nos. 1 339 012 and 1 361 537 and US Patent Application No. 2004/0084610, which disclose such an optoelectronic module, can be cited in this regard. This module thus includes, mounted on a lead frame, a first light source circuit, which is a light emitting diode, and a second photoreceptor circuit. A lens for each circuit is fixed in the encapsulation material in an aperture for each circuit, provided for such purpose. The light emitting diode generates light which passes through a first lens, whereas the photoreceptor circuit receives light reflected on an external surface by passing through a second lens.
In these patent applications, there is no description of the method of manufacturing the module while protecting the light source from any electrostatic discharge (ESD). A light source circuit of this kind can be destroyed when such discharges appear particularly by manipulating said module via external metal pins. Thus, it is often necessary to connect in more one transit diode to the light source circuit either inside said module, or outside, which is a drawback.